Lint improvements and type safety (#558)

* Clean up of lint errors
* Always return an element when requested

fire/console/encoding.py

@@ -33,6 +33,7 @@ def Encode(string, encoding=None):
   Returns:
     str, The binary string.
   """
+  del encoding  # Unused.
   return string
 
 

fire/decorators.py

@@ -107,5 +107,5 @@ def GetMetadata(fn):
 def GetParseFns(fn):
   # type: (...) -> dict
   metadata = GetMetadata(fn)
-  default = {"default": None, "positional": [], "named": {}}
+  default = {'default': None, 'positional': [], 'named': {}}
   return metadata.get(FIRE_PARSE_FNS, default)

fire/formatting_windows.py

@@ -31,7 +31,7 @@ def initialize_or_disable():
   """Enables ANSI processing on Windows or disables it as needed."""
   if HAS_COLORAMA:
     wrap = True
-    if (hasattr(sys.stdout, "isatty")
+    if (hasattr(sys.stdout, 'isatty')
         and sys.stdout.isatty()
         and platform.release() == '10'):
       # Enables native ANSI sequences in console.

fire/helptext.py

@@ -475,7 +475,7 @@ def _CreateFlagItem(flag, docstring_info, spec, required=False,
   description = _GetArgDescription(flag, docstring_info)
 
   if not flag_string:
-    flag_name_upper=formatting.Underline(flag.upper())
+    flag_name_upper = formatting.Underline(flag.upper())
     flag_string = f'--{flag}={flag_name_upper}'
   if required:
     flag_string += ' (required)'

fire/helptext_test.py

@@ -428,7 +428,6 @@ def testHelpTextMultipleKeywoardArgumentsWithShortArgs(self):
     self.assertIn('\n    --late', help_screen)
 
 
-
 class UsageTest(testutils.BaseTestCase):
 
   def testUsageOutput(self):

fire/test_components.py

@@ -554,7 +554,7 @@ def fn_with_kwarg_and_defaults(arg1, arg2, opt=True, **kwargs):
   """
   del arg1, arg2, opt
   return kwargs.get('arg3')
-# pylint: enable=g-doc-args,g-doc-return-or-yield
+
 
 def fn_with_multiple_defaults(first='first', last='last', late='late'):
   """Function with kwarg and defaults.
@@ -565,3 +565,4 @@ def fn_with_multiple_defaults(first='first', last='last', late='late'):
   """
   del last, late
   return first
+# pylint: enable=g-doc-args,g-doc-return-or-yield

fire/trace.py

@@ -77,7 +77,7 @@ def GetLastHealthyElement(self):
     for element in reversed(self.elements):
       if not element.HasError():
         return element
-    return None
+    return self.elements[0]  # The initial element is always healthy.
 
   def HasError(self):
     """Returns whether the Fire execution encountered a Fire usage error."""